21011020011021 has 4 divisors (see below), whose sum is σ = 28014693348032. Its totient is φ = 14007346674012.

The previous prime is 21011020010957. The next prime is 21011020011049. The reversal of 21011020011021 is 12011002011012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21011020011021 - 2⁶ = 21011020010957 is a prime.

It is a super-2 number, since 2×21011020011021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011020010988 and 21011020011006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011020011521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3501836668501 + ... + 3501836668506.

It is an arithmetic number, because the mean of its divisors is an integer number (7003673337008).

Almost surely, 2^{21011020011021} is an apocalyptic number.

It is an amenable number.

21011020011021 is a deficient number, since it is larger than the sum of its proper divisors (7003673337011).

21011020011021 is an equidigital number, since it uses as much as digits as its factorization.

21011020011021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7003673337010.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21011020011021 its reverse (12011002011012), we get a palindrome (33022022022033).

Subtracting from 21011020011021 its reverse (12011002011012), we obtain a square (9000018000009 = 3000003²).

The spelling of 21011020011021 in words is "twenty-one trillion, eleven billion, twenty million, eleven thousand, twenty-one".